Hydraulic pressure control device

Abstract

The hydraulic pressure control includes a valve portion which adjusts a fluid flowing into or flowing out of a hydraulic pressure chamber, a state judging portion which judges whether or not a state of the hydraulic pressure chamber is in a state in which the actual pressure is increasing even the holding signal has been inputted to the valve portion and a control portion which executes a specific control which keeps the actual pressure to the hydraulic pressure within the dead zone when the state judging portion judges that the state of the hydraulic pressure chamber is in a state that the actual pressure fluctuates even the holding signal has been inputted to the valve portion.

The invention claimed is: 
     
       1. A hydraulic pressure control device comprising
 a valve portion which adjusts a fluid flowing into or flowing out of a hydraulic pressure chamber, wherein 
 a target pressure which is a target value of a hydraulic pressure in the hydraulic pressure chamber is set and a dead zone which is a range of the hydraulic pressure between a first hydraulic pressure which is lower than the target pressure and a second hydraulic pressure which is higher than the target pressure is set, wherein 
 a pressure increasing signal or a decreasing signal is outputted to the valve portion to instruct execution of an inflow or an outflow of the fluid with respect to the hydraulic pressure chamber, so that an actual pressure which is an actual value of the hydraulic pressure in the hydraulic pressure chamber approximates the target pressure when the actual pressure is located outside the dead zone and a holding signal is outputted to the valve portion to hold the actual pressure when the actual pressure is located within the dead zone, wherein 
 the valve portion is configured to allow a fluctuation of the actual pressure generated upon execution of the inflow or the outflow of the fluid with respect to the hydraulic pressure chamber for a predetermined time period in response to the pressure increasing signal or the decreasing signal which had been inputted immediately before an inputting of the holding signal, even after the holding signal was inputted, and wherein 
 the hydraulic pressure control device further comprising: 
 
       a state judging portion which judges whether or not a state of the hydraulic pressure chamber is in a state in which the actual pressure fluctuates even the holding signal has been inputted to the valve portion; and
 a control portion which executes a specific control which keeps the actual pressure to a hydraulic pressure within the dead zone when the state judging portion judges that the state of the hydraulic pressure chamber is in a state that the actual pressure fluctuates even the holding signal has been inputted to the valve portion. 
 
     
     
       2. The hydraulic pressure control device according to  claim 1 , wherein, the state judging portion judges whether or not the state of the hydraulic pressure is in a first state in which the actual pressure is increasing even the holding signal has been inputted to the valve portion, and wherein the control portion includes a dead zone hydraulic pressure setting portion which sets a second hydraulic pressure higher than the second hydraulic pressure when the state judging portion judges that the state of the hydraulic pressure chamber is in a second state that is not in the first state, as a specific control, when the state judging portion judges that the state of the hydraulic pressure chamber is in the first state. 
     
     
       3. The hydraulic pressure control device according to  claim 2 , wherein the dead zone hydraulic pressure setting portion sets the second hydraulic pressure in response to an increasing width per unit time of the actual pressure in the first state. 
     
     
       4. The hydraulic pressure control device according to  claim 2 , wherein the second hydraulic pressure is set to a pressure higher than the target pressure by a predetermined value; and
 the dead zone hydraulic pressure setting portion executes a target pressure change processing to approximate the target pressure to the actual pressure, when the actual pressure is higher than the target pressure in the first state, in order to set a pressure higher than the second hydraulic pressure in the second state, as the second hydraulic pressure in the first state. 
 
     
     
       5. The hydraulic pressure control device according to  claim 1 , wherein
 the state judging portion judges whether or not the state of the hydraulic pressure chamber is in a third state in which the actual pressure is decreasing even the holding signal has been inputted to the valve portion; and wherein 
 the control portion includes a dead zone hydraulic pressure setting portion which sets a first hydraulic pressure lower than the first hydraulic pressure when the state judging portion judges that the state of the hydraulic pressure chamber is in a second state that is not in the third state, as a specific control, when the state judging portion judges that the state of the hydraulic pressure chamber is in the third state. 
 
     
     
       6. The hydraulic pressure control device according to  claim 5 , wherein the dead zone hydraulic pressure setting portion sets the first hydraulic pressure in response to a decreasing width per unit time of the actual pressure in the third state. 
     
     
       7. The hydraulic pressure control device according to  claim 5 , wherein
 the first hydraulic pressure is set to a pressure lower than the target pressure by a predetermined value; and wherein 
 the dead zone hydraulic pressure setting portion executes a target pressure change processing to approximate the target pressure to the actual pressure, when the actual pressure is lower than the target pressure in the third state, in order to set a pressure lower than the first hydraulic pressure in the second state, as the first hydraulic pressure in the third state. 
 
     
     
       8. The hydraulic pressure control device according to  claim 4 , wherein the dead zone hydraulic pressure setting portion executes a next target pressure change processing after a predetermined time period passed from an execution of a previous target pressure change processing, when the target pressure change processing is repeatedly executed. 
     
     
       9. The hydraulic pressure control device according to  claim 4 , wherein the dead zone hydraulic pressure setting portion executes the target pressure change processing of this time when a total amount of the change amount of the target pressure by the execution of the target pressure change processing up to the previous time is equal to or less than a predetermined defined amount, when the target pressure change processing is repeatedly executed. 
     
     
       10. The hydraulic pressure control device according to  claim 1 , wherein
 the state judging portion judges whether or not the state of the hydraulic pressure chamber is in a first state in which the actual pressure is increasing even the holding signal has been inputted to the valve portion; and 
 the control portion, as the specific control, outputs the pressure decreasing signal to the valve portion to let the fluid in the hydraulic pressure chamber flow out when the state judging portion judges that the state of the hydraulic pressure chamber is in the first state. 
 
     
     
       11. The hydraulic pressure control device according to  claim 10 , wherein the control portion stops the specific control when a value associated with a change amount of the actual pressure towards a pressure decreasing side becomes equal to or more than a predetermined value during the execution of the specific control. 
     
     
       12. The hydraulic pressure control device according to  claim 10 , wherein the control portion includes at least one threshold value in the dead zone with respect to the actual pressure and every time the actual pressure exceeds the threshold value, the control portion changes a control current which corresponds to the pressure decreasing signal to the valve portion outputted in the specific control towards an increasing side of a flowing out amount of the fluid in the hydraulic pressure chamber. 
     
     
       13. The hydraulic pressure control device according to  claim 1 , wherein
 the state judging portion judges whether or not the state of the hydraulic pressure chamber is in a third state in which the actual pressure is decreasing even the holding signal has been inputted to the valve portion, and wherein 
 the control portion, as the specific control, outputs the pressure increasing signal to the valve portion to let the fluid flow into the hydraulic pressure chamber when the state judging portion judges that the state of the hydraulic pressure chamber is in the third state. 
 
     
     
       14. The hydraulic pressure control device according to  claim 13 , wherein the control portion stops the specific control when a value associated with a change amount of the actual pressure towards a pressure increasing side becomes equal to or more than a predetermined value during the execution of the specific control. 
     
     
       15. The hydraulic pressure control device according to  claim 13 , wherein the control portion includes at least one threshold value in the dead zone with respect to the actual pressure and every time the actual pressure becomes lower than the threshold value, the control portion changes a control current which corresponds to the pressure increasing signal to the valve portion outputted in the specific control towards an increasing side of a flowing-in amount of the fluid into the hydraulic pressure chamber. 
     
     
       16. The hydraulic pressure control device according to  claim 10 , wherein the control portion executes the specific control of this time at least after a second predetermined time in which a reaction can be detectible in case the reaction appears in the actual pressure by the specific control from the execution of previous specific control, when a plurality of specific controls is executed.